Ancylostoma duodenale

Ancylostoma duodenale is a hookworm species belonging to the family Ancylostomatidae. It is a nematode, which is characterized by having an earthworm-like form but not segmented. It is whitish in color. The species is a parasite of humans. Its typical site of infection is the intestinal wall. It has distinctive two pairs of teeth (or ventral plates) on its buccal cavity that it uses to attach to the wall of the intestine. It feeds on blood and therefore may cause iron deficiency anaemia to its host. Infestation with Ancylostoma spp. is referred to as ancylostomiasis.

The males are 8mm to 11 mm in length whereas the females are 10mm to 13mm long. The males have a copulatory bursa and needle-like spicules with tiny tips whereas the females have a vulva at the posterior end. The infective stage is the larval phase. The larva penetrates the exposed skin and finds its way to the bloodstream to be carried to the lungs. It then breaks into the alveoli to reach the bronchi and trachea where it would be swallowed to reach the small intestine.

This species is widespread in temperate areas, in contrast to the more tropical distribution of the new world hookworm, Necator americanus. It is the only hookworm found in the U.S. It is also abundant in Europe, north Africa, India, China, and southeast Asia.